New Synthesis of (11Z,13Z)-11,13-Hexadecadienal, the Female Sex Pheromone of the Navel Orangeworm

(11Z,13Z)-11,13-Hexadecadienal, the female sex pheromone of the navel orangeworm (Amyelois transitella), was synthesized from commercially available 10-bromo-1-decanol in a 27% overall yield (8 steps). The synthesis was achieved by using 10-iododecanal, trimethylsilyl-acetylene and (Z)-1-bromo-1-butene as the key building blocks, employing Sonogashira-Hagihara coupling and Brown's hydroboration-protonolysis as the key reactions. The terminal formyl group was installed in the earlier stage of the synthesis rather than in the final step. This procedure enabled the multi-gram-scale preparation of this economically important pheromone.